During the fabrication of photovoltaic devices, layers of semiconductor material can be applied to a substrate with one layer serving as a window layer and a second layer serving as the absorber layer. The window layer can allow the penetration of solar radiation to the absorber layer, where the optical power is converted into electrical power. Some photovoltaic devices can use transparent thin films that are also conductors of electrical charge. The conductive thin films can include transparent conductive layers that contain a transparent conductive oxide (TCO), such as fluorine-doped tin oxide, aluminum-doped zinc oxide, or indium tin oxide. The TCO can allow light to pass through a semiconductor window layer to the active light absorbing material and also serve as an ohmic contact to transport photogenerated charge carriers away from the light absorbing material. A back electrode can be formed on the back surface of a semiconductor layer. The back electrode can include electrically conductive material, such as metallic silver, nickel, copper, aluminum, titanium, palladium, chrome, molybdenum or any practical combination thereof.